As said here before, this is not rocket science, really. Just technique. Let me illustrate with a portrait of a student in my class an hour or so ago:
CAMERA – Set your camera to MANUAL mode. Select, say, 1/125th second at f/5.6 and 400 ISO. This will make the ambient light disappear so the only light is your flash.
FLASH – Use an on-camera flash. Make sure this flash is in TTL mode. Since you are shooting against a white wall, turn flash exposure compensation (“FEC”) to +1 stop.
AIM: Start by aiming the flash straight at your subject. Baaad:
(Just look at the shadows, the deer-in-the-headlight look, the skin, the shadows: Ouch!)
To improve this, now aim the flash behind you, upward at 45 degrees:
Much better. Especially for women.
But for even better results., often used for men, now turn the flash to your right, and still 45 degrees upward. Now you get Rembrandt lighting:
Simple, innit?
Go try this right now!
When turning the flash to the right, do you mean right and forward, right and to the rear, or directly right? Should remain angled up 45 degrees?
It depends on where you want the light to come from. Look at your model, then draw an imaginary line from the model to “where the umbrella should be”, then aim your flash there. Usually that may well mean directly right, but angled up at 45 degrees.